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Thursday, November 17, 2011

Is the oral contraceptive pill fueling prostate cancer?

People who know better - i.e., cancer researchers who are working at the molecular level and not at the macro level of patient care - have been arguing for years that estrogen exposure (either endogenous or exogenous) is a greater risk factor for prostate cancer than testosterone, which is often still blamed.

In fact, one of the front-line approaches to prostate cancer, despite the evidence that estrogen is the fuel for many cancers (including prostate cancer), is androgen depletion therapy (which has side effects like gynecomastia, diabetes, depression, bone loss, and heart disease, to name a few).

But now there is new evidence that exposure to the chemicals in oral contraceptives may seriously increase the risk for prostate cancer.

This is only a correlation study - they have not shown cause and effect. And they indicate it's not so much exposure to the chemicals during intercourse (which would be a good reason to switch to a different form of birth control, like vasectomy), but that these chemicals are in the drinking water.

The Pill became publicly available in the 1960s and remains a popular choice of contraceptive

Scientists say research is needed to ascertain if oral contraceptive pill use could be fuelling rising prostate cancer rates.

A Canadian team told the British Medical Journal they had found a possible link.

But experts stress this is not proof that one causes the other and it might be a fluke finding. The researchers believe estrogen by-products in the urine of pill-users may be entering food and drinking water.

The hormone is known to feed the growth of certain cancers.

The latest investigation looked at data from 2007 for individual nations and continents worldwide to see if there was any link.

The researchers found a significant association between contraceptive pill use in the population as a whole with both the number of new cases of, and deaths from, prostate cancer.

This link was irrespective of the nation's wealth, suggesting it might not be down to better disease detection in more affluent countries that also tend to have higher rates of oral contraceptive use.

And it was strongest in Europe.

Additionally, they found no link between prostate cancer and other forms of contraception, like the coil, suggesting it is not something that is sexually transmitted or associated with intercourse itself.

Drs David Margel and Neil Fleshner, from Toronto University, fear that contamination of the food chain with hormones originating from the pill are the likely culprit.

They stress that their work merely suggests a link and is not proof.

"It must be considered hypothesis generating and thought-provoking," they say in their BMJ Open report.

They said more investigations are needed and recommend close monitoring of environmental levels of oral contraceptive by-products or endocrine disruptive compounds (EDCs).

Dr Kate Holmes, of The Prostate Cancer Charity, agreed that more research was warranted.

"While this study raises some interesting questions about the presence of EDCs in the environment, it does not contribute to our overall understanding of the development of prostate cancer."

Jessica Harris, of Cancer Research UK, said uncertainty about the disease remained. "Comparing the rates of two apparently unrelated issues across countries is a notoriously unreliable way of establishing whether they are truly linked, because so many things vary between different countries that it's impossible to say whether one thing is causing the other.

"It has been difficult to identify factors that affect the risk of prostate cancer, but we know that men are at higher risk as they get older, or if they have a strong family history of breast or prostate cancer. The disease is also more common in black men than white or Asian men."